The present invention relates to novel metal alloy compositions and more particularly to copper-lead alloys and the use of particles of such alloys in lubricant compositions.
Every combustion engine undergoes a continuous process of scratching of the internal surfaces by millions of minute particles that circulate with the engine oil. These particles are hard and arise from asperities that exist on all metal surfaces. No matter how smooth these surfaces feel or appear to the eye, each time a piston moves inside the cylinder, a number of these opposing asperities contact each other. This repeated contact results in the generation of tremendous pressure and heat causing instant microwelding of the asperities to each other. This repeated contact results in the generation of tremendous pressure and heat causing instant microwelding of the asperities to each other. Because the welded asperities are so small, they cannot stop the motion of the moving part, they are sheared, producing tiny particles which are instantly quenched in the motor oil resulting in the formation of hard metal particles. These particles are small and those that are not trapped by the filter can circulate with the motor oil through the engine, repeatedly.
The circulating particles cut scratches in the metal surfaces which results in the production of more asperities. This continuous microwelding and hard particle generation promotes accelerated wear in the engine. The scratches on the cylinder walls and piston rings also serve as miniature escape channels causing compression leaks. During the compression stroke, gas and air mixture blows by through the scratches and when the combustion occurs, explosive power is reduced. Signs of scratches and blowby are manifested as reduced compression and horsepower, increased oil burning usage, and reduced gas mileage.
These engine frictional losses associated with the operation of automotive type equipment account for approximately 5-15% of the energy required to drive such equipment, and are found primarily in the piston ring and skirt area, bearings, valve train, and within the lubricant itself.
Conventionally, special oil additives such as "STP" or the like are often used to reduce friction or lower wear. A significant proportion of these losses can sometimes be restored by modifying the engine oil in service with solid film lubrication. The friction modification capabilities of solid lubricants such as molybdenum disulfide and graphite are well documented. While possessing low coefficients of friction, (0.19 and 0.18 respectively), graphite and molybdenum disulfide still cannot match the coefficient of friction of PTFE, typically 0.04-0.12.
Attempts have been made in the past to employ fine particle size copper-lead alloys as lubricant additives. For example, U.S. Pat. Nos. 3,894,957; 3,719,477; and, 3,556,779 all relate to producing what are alleged to be homogenous copper-lead alloys and/or the use of such alloys in lubricant compositions. U.S. Pat. No. 3,894,957 uses from about 0.25 to about 5% alloy based on the weight of the oil, the alloy containing from about 5 to about 55% lead, preferably 20 to 45% lead, 95 to 45% copper, preferably 80 to 55% copper, with up to 10% by weight of other metals, preferably zinc or tin and trace amounts of a homogeneity promoter. In many cases, such compositions exhibited better properties than previously known compositions, but there was still evidence of significant wear and failure to fully restore lost power and compression because the alloy particles were not truly homogeneous.
One object of the present invention is to produce homogenous fine grained high lead bearing copper alloys having a very fine microstructure.
Yet another object of the present invention is to provide copper-lead alloys containing up to 60% or more by weight lead.
A still further object of the present invention is to provide lubricant composition containing fine particles of such alloys.